Novitates Gabonenses 93: a fresh look at Podostemaceae in Gabon following recent inventories, with a new combination for Ledermanniella nicolasii Author Bidault, Ehoarn https://orcid.org/0000-0001-5029-8069 Missouri Botanical Garden, Africa & Madagascar Department, St. Louis, Missouri, USA & Institut de Systematique, Evolution, et Biodiversite (ISYEB), Unite Mixte de Recherche 7205, Centre National de la Recherche Scientifique / Museum National d'Histoire Naturelle / Ecole Pratique des Hautes Etudes, Universite Pierre et Marie Curie, Sorbonne Universites, Paris, France ehoarn.bidault@mobot.org Author Boupoya, Archange https://orcid.org/0000-0002-8926-8737 Institut de Recherche en Ecologie Tropicale (IRET), Libreville, Gabon & Herbier National du Gabon, Libreville, Gabon Author Ikabanga, Davy U. Laboratoire d'Ecophysiologie et de Biodiversite Vegetale, Departement de Biologie, Faculte des Sciences, Universite des Sciences et Techniques de Masuku (USTM), Franceville, Gabon Author Nguimbit, Igor Laboratoire d'Ecophysiologie et de Biodiversite Vegetale, Departement de Biologie, Faculte des Sciences, Universite des Sciences et Techniques de Masuku (USTM), Franceville, Gabon Author Texier, Nicolas https://orcid.org/0000-0002-4045-992X Missouri Botanical Garden, Africa & Madagascar Department, St. Louis, Missouri, USA & Evolutionary Biology and Ecology Unit, Faculte des Sciences, Universite Libre de Bruxelles, Brussels, Belgium Author Rutishauser, Rolf Herbarium et Bibliotheque de Botanique africaine, Universite Libre de Bruxelles, Brussels, Belgium Author Mesterhazy, Attila https://orcid.org/0000-0001-7952-5990 Department of Systematic and Evolutionary Botany, University of Zurich, Switzerland Author Stevart, Tariq https://orcid.org/0000-0002-6212-0361 Missouri Botanical Garden, Africa & Madagascar Department, St. Louis, Missouri, USA & Evolutionary Biology and Ecology Unit, Faculte des Sciences, Universite Libre de Bruxelles, Brussels, Belgium & Centre for Ecological Research, Wetland Ecology Research Group, Debrecen, Hungary text Plant Ecology and Evolution 2023 2023-03-01 156 1 59 84 http://dx.doi.org/10.5091/plecevo.96359 journal article http://dx.doi.org/10.5091/plecevo.96359 2032-3921-1-59 A3301095CCAD56078E5F4CA25FE7E738 Inversodicraea boumiensis (C.Cusset) Cheek (Cheek and Haba 2016: 55) Figs 3C , 4A Ledermanniella boumiensis C.Cusset ( Cusset 1983 : 370, plate 3) Type . GABON • Boumi waterfalls at Mbigou [" Chutes de la Boumi a Mbigou"]; 5 Jul. 1927 ; [ 1°54 '16" S , 11°54 '31" E ]; 665 m ; fl., fr.; Le Testu 6536 ; holotype : P [P00179270]; isotypes: BM [BM000910485], BR [BR0000006267230], P [P00179271] . Distribution. Endemic to the Louetsi river, south-eastern Gabon. Before 2017, this species was only known from a single collection made at Boumi falls, near Mbigou. In 2018, it was discovered at two additional sites on the same river, at Issala and Dibwangui. Habitat and ecology. Rapids and falls in rivers from ca 30 to 50 m wide, 380-665 m in elevation. It appears to be very rare at the sites where it has been encountered. Flowers and fruits were collected in July and August. At Dibwangui, it grows intermingled with I. aff. annithomae , in strong currents. Notes. Inversodicraea boumiensis can be distinguished from I. annithomae mainly by its much smaller stature (stem <1 mm thick and up to 2-3 cm long vs stem up to 3 mm thick and 20 cm long), stem scales (thin and spreading in I. boumiensis vs thick and appressed in I. annithomae ), and pollen as dyads (vs monads in I. annithomae ). The collection Letouzey 15339 from the Ntem river (Cameroon) was attached to I. boumiensis by Cusset, but later determined as I. tchoutoi ( Cheek et al. 2017 ). After examination of this collection, we choose to follow Cheek et al. (2017) .